31 



I ^Vl/ 



57 



tr.^ 



UNITED STATES PUBLIC HEALTH SERVICE 

RUPERT BLUE, Surgeon General 



MEMORY TESTS OF SCHOOL CHILDREN 

MEMORY SPAN OF 1,585 WHITE SCHOOL CHILDREN 
(751 BOYS, 834 GIRLS) IN THE CITY OF X 



BY 

■ C. W. STILES 

Professor of Zoology 
United States Public Health Service 



L 



REPRINT No. 316 

FROM THE 

PUBLIC HEALTH REPORTS 

December 24, 1915 
Pages 3738-3745 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1916 



Monograph 



D. of D. 
nB 19 1916 




MEMORY TESTS OF SCHOOL CHILDREN.^ 

MEMORY SPAN OF 1,585 WHITE SCHOOL CHttDREN (751 BOYS, 834 GIRLS) IN THE 

CITY OF X.i 

By C. W. Stiles, Professor of Zoology, United States Public Health Sen-ice. 

Of the 1,585 children (751 boys, 834 girls) for whom memory-span 
data are available, 1,223 (586 boys, 637 girls) belong to group S 
(from homes provided with sewer connection, but without privies), 
271 (106 boys, 165 girls) belong to group P (from homes with privy 
sanitation), and 91 (59 boys, 32 girls) to group U (from homes of 
unknown sanitation). 

In taking the memory span the following table was used : 

Table 1. — Strong's memory-span numbers.^ 

3 years old: 2 numbers: 7-2 

1-6 
8-1 

4 years old: 3 numbers: 7-4-8 

2-9-4 

6-3-7 
6 years old: 4 numbers: 5-1-8-3 

9-2-7-4 

5-9-2-6 
8 years old: 5 numbers: 4-7-3-9-5 

7-4-2-8-1 

5-8-3-7-6 
10 years old: 6 niimbers: 8-5-4-7-2-6 

2-7-4-6-5-1 

9-4-1-7-3-8 
12 years old: 7 numbers: 2-9-6-4-3-7-5 

9-2-8-.5-1-6-4 

1-3-9-5-8-4-7 

8 numbers: 4-7-2-9-3-8-1-5 

7-1-8-3-6-2-9-5 
4-6-1-5-8-2-9-7 

9 numbers: 9-2-4-7-3-8-6-1-5 

4-7-5-2-9-6-3-1-8 
9-5-8-3-7-2-6-4-1 
10 numbers: 8-3-9-5-1-6-2-7-0-4 
2-1-4-6-0-7-3-8-5-9 
4-0-5-2-8-1-7-9-6-3 

1 Reprint from the Public HeaUh Reports, vol. 30, No. 52, Dec. 24, 1915, pp. 3738-3745. For other 
articles on the city of X see Public Health Reports, 1915, as follows: Difficulties in obtaining ages, v. 
30(5), Jan. 29, pp. 310-311; Zooparasitic intestinal infections, v. 30(27), July 2, pp. 1991-2002; School 
grades, V. 30(28), July 9, pp. 2060-2067; Tobacco and snufl, v. 30(40), Oct. 1, pp. 2926-2928; Heights and 
weights of children, v. 30(41), Oct. 8, pp. 2990-3003; I-ung capacity, v. 30(42), Oct. 15, pp. 3067-3072. 

2 Prepared by E. K. Strong, jr., professor of psychology, George Peabody College for Teachers, Nashville, 
Tenn. 

21096—16 e q 



4 MEMORY TESTS OF SCHOOL CHILDEEN. 

Method of giving the memory span. — In giving the memory-span 
test, we followed the method used by psychologists and psychia- 
trists. The test was explained to each child separately. The 
tester would then begin with the first line of the foregoing table and 
repeat deliberately and in a monotone: "Seven [very short pause], 
two." If the child failed to repeat these numbei-s in the order 
given, he was granted a second chance on the next line: "One, six." 
If he failed on this, he was given a third chance on the third line: 
*' Eight, four." Not* more than three chances were given on any 
one series of (2, 3, 4, 5, — x) numbers. As soon as a child repeated 
the 2, 3, 4, or x numbers in any series, he was tested on the next 
higher series. (It will be noticed that one extra number is added 
in each series. See foregoing table.) This was continued until the 
pupil failed three times on a group. He was accredited with the 
highest number of figures he could repeat without error. The tests 
were given by local substitute school teachers, who were, of course, 
given preliminary practice. 

As I have seen this test given by other investigators, two different 
''stage settings" have been used. Some investigators have the 
"subject" in a room that is perfectly quiet and free from distraction 
(other than the distraction of isolation); others have the "subject" 
in a room that is not necessarily perfectly quiet and in which there 
is or may be some distraction in the way of noise or movement. 
There are certain arguments in favor of both methods. 

In our tests separate rooms were impossible, even if desirable. 
Tlie tests were made in a very large school assembly hall and the 
substitute school teachers were placed at intervals around the room. 

The pupils passed from one teacher to another for certain different 
mental and physical tests. The confusion was about equal to that 
found in the average classroom of a weU-regulated Southern school. 
In other words, the children were tested under conditions that cor- 
responded as closely as possible to their daily school life. Most of 
the children looked upon the tests in the light of playing games; 
some of the pupils were not so thorouglily at their ease. 

That some children did better work with this "stage setting" 
than they would have done if entirely isolated from the other children 
seems practically certain; that the reverse holds for other children 
is equally certain. For instance, a certain girl gave a memory 
span of 8 numbers; personally, I tested this same girl at her home 
on several occasions, and she repeatedly showed a memory span of 
9 and 10 numbers. 

The personal equation, as to nervousness, diffidence, etc., can not 
be entirely eliminated, but the results obtained show what can be 
reasonably expected of city school children (white) in the locality in 
question and with the "stage setting" that was used. 



MEMORY TESTS OP SCHOOL CHILDREN. 



Table 2. — Memory span of 751 boys, 6 to 17.75 years old, inclusive, of the city of X, 
summarized by quarter-year periods, total-year periods, and sanitary groups. 

[P= children from homes provided with a privy; S= children from homes with sewer connection but with- 
out a privy; U=home sanitation unknown; T= total of P, S, and U.| 



Age. 


Number in memory span, with num- 
ber of children attainmg each span. 


Num- 
ber 
of 
pu- 
pils. 


Memory 
span. 


3 


4 


5 


6 


7 


8 


9 


10 


11 


To- 
tal. 


A ver- 
age. 


6.00 T 




1 
3 
3 

2 

8 

1 
















1 

6 
12 
10 
23 

5 

1 
29 
17 
21 
18 
17 
57 
13 

3 
73 
18 
16 
23 
22 
65 
12 

2 
79 
24 
22 
25 
21 
76 
12 

4 
92 
23 
27 
25 
22 
75 
12 
10 
97 
26 
25 
20 
15 
60 
21 

5 
86 
17 
18 
22 
13 
52 
10 

8 

70 
15 
15 
57 
13 
56 

9 

5 

70 

14 

19 

12 

4 

38 

3 

8 

49 

13 


4 

28 

63 

59 

121 

28 

5 

154 

94 

118 

100 

95 

326 

67 

14 

407 

112 

99 

144 

143 

413 

73 

12 

498 

158 

141 

160 

134 

500 

70 

23 

593 

151 

186 

167 

154 

513 

78 

67 

658 

1«76 

163 

128 

97 

397 

136 

31 

564 

109 

128 

155 

91 

354 

73 

56 

483 

97 

104 

187 

93 

385 

58 

38 

481 

93 

139 

89 

30 

269 

23 

59 

351 

91 


4.00 
4.67 
5.25 
5.90 
5 ''6 


6.25 T 




2 
3 
2 
5 
1 
1 
7 
5 
6 
9 
6 
21 
•4 
1 
26 
3 
3 
2 
4 
9 
3 


1 
6 
2 

7 
2 












6.50 T 














6.75 T. 




3 
2 
1 


1 

1 








6S 










6P 










5 60 


6U 












5 00 


6T 




9 
3 

1 
1 
2 

3 

4 

7 


9 
6 

11 
5 
6 

23 
4 
1 

28 
9 
4 

13 
6 

25 
5 
2 

32 
5 

11 
5 
5 

20 
4 
2 

26 
5 
6 

11 
4 

17 
6 
3 

26 
7 

10 
9 
7 

26 
6 
1 

33 
9 
6 
5 
3 

18 
3 
2 

23 
7 
2 
4 
1 

13 
1 


3 
3 
1 
3 
3 
9 
1 


1 








5 31 


7.00 T 










5 53 


7.25 T 


1 


1 








5 62 


7.50 T 








5 55 


7.75 T 












5 59 


7S 




1 








5 72 


7P 










5 15 


7 U 


1 
1 










4 67 


7T 


10 
5 
4 

.8 
9 

22 
4 


1 
1 
3 


• 






5 57 


8.00 T 








6 22 


8.25 T 




2 








6 19 


8.50 T 










6 26 


8.75 T .. 






3 

7 








6 50 


8S 




^ 








6 35 


8P 










6.08 


8U 














6 00 


8T 




2 

i 

2 
2 

1 
5 


12 
4 
1 
5 
5 

10 
5 

'is" 

6 
1 
1 
2 
8 
1 
1 
10 
3 
3 
.... 

6 

1 

"Y 

2 


26 

9 

4 

8 

■ 5 

22 
3 
1 

26 
6 

17 
9 
8 

33 
3 
4 

40 
7 
8 
6 
6 

11 

13 
3 

27 
3 
6 
9 
4 

15 
3 
4 

22 
6 
7 

12 
6 

23 
6 
2 

31 
1 

10 
1 
1 
7 
1 
5 

13 
3 


7 
4 
3 
4 
5 
16 








6 30 


9.00 T 




1 
.... 






6 58 


9.25 T 




1 




6 41 


9.50 T.. . . . 




6 40 


9.75 T 








6 38 


9.S . . .... 




2 


1 




6 58 


9 P 




5 83 


9 




1 

6 










5.75 


9T 




16 
5 
1 
3 

8 
13 
2 
2 
17 
6 
4 
3 
1 
14 


2 
1 
2 
1 


1 




6.45 


10.00 T 




6.57 












6 89 


10.50 T 










6 68 


10.75 T. 










7 00 


10 S 






4 






6 84 












6.50 


10 U 












6 70 


10 T 






4 
2 






6.78 


11.00 T 




1 






6.77 


11.25 T 








6 52 


11.50 T 




2 








6.40 












6 47 


US 




1 
1 
1 
3 


2 






6.62 


HP 








6 48 


11 u 












6.20 


11 T.... . . 




14 
3 

4 
3 
2 
10 

"2 
12 

"3 
8 
5 

13 


2 






6 56 


12.00 T 








6.41 


12.25 T 






2 
2 
1 
4 
1 






7.11 


12.50 T 






2 
2 
5 
1 


1 

1 




7.05 


12.75 T 






7.00 


12 S 






6.81 








2 




7 30 


12 U 






7 00 


12 T 






6 

"2 
3 

1 
4 
2 


5 
1 

1 


2 




6.90 


13.00 T 




1 


6 47 


13.25 T .. 








6 93 


13.50 T 










6 93 


13.75 T 












7.15 


13 S 




1 


2 






6.87 


13 P.... 








6 44 


13 U 






3 

16 
4 
6 
5 
1 

11 
2 
3 

16 
1 








7 60 


13 T... . . . 




1 
1 


6 
1 

1 
1 


14 
6 
1 
3 
1 

11 


2 

1 

"i' 
1 
3 






6 87 


14.00 T 








6.64 






1 
1 




7 32 


14.50 T 






7.42 


14.75 T.. . .... 






7.50 


14S 




1 


3 


2 




7.08 






7.67 


14 U 
















7.37 


14 T 




1 


3 
2 


11 

4 


3 

2 


2 
1 




7.16 


15.00 T 




7.00 



6 MEMORY TESTS OF SCHOOL CHILDREN. 

Table 2. — Memory span of 751 hoys, 6 to 17.75 years old, inclusive, of the city of X, 
summarized by quarter-year periods, total-year periods, and sanitary groups — Contd. 



/ 
Age. 


Number in memory span, with num- 
ber of children attainmg each span. 


Num- 
ber 
of 
pu- 
pils. 


Memory 
span. 


3 


4 


5 


6 


7 


8 


9 


10 


11 


To- 
tal. 


Aver- 
ago. 


15 25T 






1 


"i' 

4 
5 
1 
3 

9 
2 


7 
6 
6 

IS 
1 
3 

22 
1 
3 
7 
2 

11 
1 
2 

14 
1 
1 
2 
1 
4 
1 


5 
1 
4 
9 
1 
1 
11 
1 
4 
5 

"'9' 

1 


5 






18 
8 

15 

41 
4 
9 

54 
8 
8 

17 
3 

31 
3 
2 

36 
4 
4 
5 
3 

12 
2 
2 

16 


139 
56 

103 

294 
30 
6.3 

3S9 
55 
62 

127 
23 

22s 
25 
14 

267 
27 
33 
38 
22 
92 
13 
15 

120 


7.72 


15.50 T 










7.00 


15.75 T 






1 
4 








6.S7 


15 S 








1 




7.17 


15 P 






7.50 


15 U 












7.22 


15 T 






4 
4 


1 




7.20 


16.00 T 






6. 87 


16.25 T 












7.75 


16.50 T 








3 


2 




7.47 


16.75 T 








7.67 


16 S 








7 


1 

1 




7.35 


16 P 








8.33 


16 U 










7.00 


16 T 








7 
2 


10 

1 
1 
1 

"'3' 




2 




7.42 


17.00 T 








6.75 


17.25 T 














8.25 


17.50 T 


' 






1 
1 
2 
1 

1 
4 


1 




7.60 


17.75 T 








7.33 


17 S 








1 




7.67 


17 P 








6.50 


17U 










3 






7.50 


17T 








5 


3 


1 




7.50 













Table 3. — Memory span of 834 girls, 6 to 17.75 years old, inclusive, of the city of X, 
summarized by quarter-year periods, total-year periods, and sanitary groups. 

[P= children from homes provided with a privy; S=children from homes with sewer connection but with- 
out a privy; U=home sanitation unlcnown; T=total of P, S, and V.] 



Age. 


Number in memory span, with num- 
ber of children attaining each span. 


Num- 
ber 
of 
pu- 
pils. 


Memory 
span. 


3 


4 


5 


6 


7 


8 


9 


10 


11 


To- 
tal. 


-Vver- 
age. 


6.00 T 








1 

1 
6 
2 
9 

1 


1 

1 

.... 

2 
1 










2 
10 
12 

7 
27 

3 

1 
31 
15 
18 
15 
13 
39 
16 

6 
61 
18 
11 
17 
19 
46 
17 

2 
65 
19 
20 
24 
15 
53 
21 

4 
78 
25 


13 

52 

68 

38 

149 

18 

4 

171 

76 

111 

84 

68 

218 

90 

31 

339 

102 

69 

103 

119 

288 

96 

9 

393 

119 

134 

157 

104 

365 

126 

23 

514 

1.58 


6.50 


6.25 T 




1 

1 

1 


7 
4 










5.20 


6.50 T 




1 


[ 




5.67 


6.75 T 








5.43 


6S 




2 1.'? 


1 








6.52 


6P 






1 








6.00 


6U 




1 










4.00 


6T 




3 
4 
1 
1 
3 
6 
2 
1 
9 
4 


14 
6 
5 
6 
6 

14 
5 
4 

23 
2 
3 
4 
3 
9 
2 
1 

12 
3 
1 
4 
1 
3 
4 
2 
9 
3 


10 
5 
6 
6 
2 

12 
7 

"w 

6 
4 
9 
6 
15 
10 


3 


1 








5.52 


7.00 T 










5.07 


7.25 T 




2 
2 
2 

4 
1 
1 
6 
3 
2 
3 
4 

10 
2 


4 








6.17 


7.50 T 










5.60 


7.75 T 












6.23 


7S 




3 
1 








5.59 


7P 










5 62 


7U 










5.17 


7T 




4 
2 
2 
1 
4 
9 








5.56 


8.00 T 


1 








5 67 


8.25 T 








6.27 


8.50 T 












6.06 


8.75 T 1 


2 
2 
3 

1 
6 
1 

1 








6.26 


8S 


1 








6 26 


8P 








5.65 


8U 












4.50 


8T 


1 
1 


25 
6 
5 
7 
2 

12 
7 
1 

20 
9 


12 
3 

10 
10 
9 
24 

7 

1 

32 

8 


9 
5 
2 
2 
3 
11 
1 








6.05 


9.00 T 








6 26 


9.25 T 


1 

1 






6.70 


9.50 T 








6.54 


9.75T 










6.93 


9S 




1 
1 


2 






6.89 


9P 


1 






6.00 


9U 








6.75 


9T 


1 


2 
2 


12 
2 


2 

1 






6.59 


lO.OOT 






6.32 



MEMOEY TESTS OF SCHOOL CHILDREN. 



Table 3. — Memory span of 834 girls, 6 to 17.75 years old, inclusive, of the city of X, 
summarized by quarter-year periods, total-year periods, and sanitary groups — Continued. 



Age. 


Number in memory span, with num- 
ber of children attaining each span. 


Num- 
ber 
of 
pu- 
pils. 


Memory 
span." 


3 


4 


5 


e 


7 


8 


9 


10 


11 


To- 
tal. 


Aver- 
age. 


10.25 T 






2 

7 

2 

13 

1 


8 
6 

10 

22 

10 
1 

33 
9 
3 
7 
4 

17 
5 
1 

23 
3 
8 
5 
7 

17 
5 
1 

23 


6 

22 
6 


2 
2 
2 
6 
2 


1 
.... 

1 
2 






20 
24 
22 
69 
21 

1 
91 
26 
12 
31 
10 
60 
17 

2 
79 
14 
18 
28 
17 
59 
15 

3 
77 
14 
21 
31 
27 
75 
15 

3 
93 
26 
19 
31 
14 
66 
19 

5 
90 
22 
17 
19 
13 
56 
14 

1 
71 
16 
21 
19 
12 
58 

6 

4 
68 
11 

8 

4 

7 
29 

1 


129 
150 
144 
434 
141 
6 
581 
170 

S5 
21s 

71 
415 
116 

13 
544 

99 

lis 

190 
124 
403 
107 

21 
531 

96 
156 
223 
192 
540 
104 

23 
607 
177 
142 
217 
101 
4G9 
131 

37 
637 
159 
124 
137 

88 
406 

96 
6 
508 
113 
148 
1.39 

88 
421 

41 

26 
488 

87 

61 

34 

49 

223 

8 




10.50 T 








6 25 


10.75 T 






10 S 










6.29 


10 P 




10 u 










6.00 
6.38 
6.54 
7.08 
7.03 
7.10 
6.92 
6 82 


10 T 






14 
2 


28 

10 
6 

14 
2 

20 

11 
1 

32 
8 
2 
9 
3 

18 
3 
1 

22 
4 

10 
8 
8 

28 
5 
1 

34 
7 
7 
5 
3 

18 
4 

'22' 
11 
10 
8 
5 
26 
7 


8 
4 
2 

8 
1 
15 


3 






11.00 T 




11.25 T 




1 
1 

1 
2 

1 






11.50 T 












11.75 T 








1 

1 


lis 






11 P 




11 U 












6.50 
6.89 
7.07 
6. .56 
6.79 
7 29 


11 T 








15 
2 
4 
8 
4 

14 
3 
1 

IS 
8 
6 
8 
9 

19 
4 
2 

25 
5 
6 
8 
6 

20 
3 
2 

25 
7 
6 
4 
1 

16 
2 


3 

1 

.... 

1 

""3' 






12.00 T 




12.25 T 












12.50 T 




12.75 T 




2 
3 




12 S 








6.83 
7 13 


12 P 




12 U 










7 00 


12 T 








3 
2 
3 
3 

1 
6 
1 


3 




6.90 
6.86 
7.43 
7 19 


13.00 T 




13.25 T 






3 
6 
2 


1 
6 
5 
13 
3 






13.50 T 






2 
1 
3 




13.75 T 






7 11 


13 S 






7.20 
6.93 
7.67 
7 17 


13 P 






13 U 










13 T 






8 

1 


16 

10 
3 

12 
3 

19 
7 
2 

28 
4 
1 
2 
2 
6 
2 
1 
9 
3 
4 
3 
2 
7 
2 
3 

12 
2 
1 


7 
1 

3 
3 

1 
5 
2 
1 
8 
1 


3 




11.00 T 






6.81 
7 47 


14.25 T 








14.50 T 






1 

1 
2 
1 


1 




7 00 


14.75 T 




7 21 


14S .. .. 






1 

1 




7 11 


14 P 




6 89 


14 U 




7 40 


14 T 






3 


2 




7 08 


15.00 T 




7 23 


15.25 T 












7 29 


15.50 T 






2 
2 
2 
2 


3 

1 
4 

1 






7 21 


15.75 T 






1 
1 




6.77 
7 25 


15 S 




15P 




6 86 


15 U 









6 00 


15T 




1 




33 
7 
9 
8 
4 

25 
3 

"28' 
3 
2 

1 
1 
7 


18 
4 
7 
7 
6 

22 
1 
1 

24 
1 
4 
1 
2 
7 
1 


5 
1 


1 




7 15 


16.00 T 




7 06 


16.25 T 










7 05 


16.50 T 






1 






7.32 


16.75 T 












7 33 


16 S 








2 






7.26 


16 P 










6 83 


16 U 












6.50 










2 
4 
1 
1 
1 
7 






7 18 


17.00 T 






1 




7.91 


17.25 T 








7.62 


17.50 T 








1 


8 50 


17.75T 








2 
5 






7.00 


17S 






2 




7.69 


17 P 






8.00 


17 U 












1 






17 T 








5 


7 


8 


7 2 





30 


231 


7 70 















Cont'parison hy total-year periods and sex groups. — If the total-year 
periods be compared (see chart 1), it is seen that there is in general 
a gradual increase in the memory span from the younger to the older 
groups. This increase is not, however, regular from year to year, 
for in the boys the 10-year-old period excelled the 11-year-old period, 



8 



MEMORY TESTS OF SCHOOL CHILDEEN. 



and the 12-year-old period excelled the 13-year-old period; among, 
the girls the 9-year-old period excelled the 10-year-old period, and 
the 13-year-old period excelled the 14- and 15-year-old periods. 

If the two sex groups (chart 1) for each year be compared, it is 
seen that neither sex uniformly excelled the other; in 5 total-year 
periods (6, 9, 11, 13, and 17 years) the girls excelled the boys; and 
in 6 total-year periods (7, 8, 10, 14, 15, and 16 years) the boys excelled 
the girls, but the difference in one instance is negligible; the boys 
and girls were equal, or practically equal, in 2 periods (7 and 12 years). 

The conclusion would therefore seem to be justified that no essential 
difference was shown between the memory spans of the two sexes, 
and that while there was in general a gradual increase in the aver- 
age memory span from younger to older children, this increas3 did 
not express itself in exact ratio to age. Considering the matter from 
a standpoint of the average of accomplishment per year in chrono- 
logical age rather than the average per year in mental age, it would 



Memory Span in Nl/mberj 


Chart -I. 
FOR 748 kVHiTEBoYS/iND 833 White Girls 6.00 to 17.75 tears old, inclusive,- Co 


tINTY OF X. 


8.OT 

7.OT 
1 


b Years 


7 Yt«R5 


8 Yeabs 


9YtAB5 


IOYears 


II Years, 


I2YEAB1 


I3YEAR5 


I4YEAR5 


IS Years 


|5Yej>r«, 


I7YEAR5 
























p— s — 




1 


1 ^=J 


=3^3-< 


^^ 


—ii 

f: 


— i — 1 


— * 




—^ 


\—t — d 
— ^ — 


'4 


— s-^^ 
— iT- 


k°=r — 


r\ 




—^ 














EE^E 



V5. Pueuc Health Service 



appear reasonable to expect that the average white child, boy or girl, 
in the locality in question, and in the ''stage setting" used, will show 
the following memory spans: 

Numbers. 

Children 6 and 7 years old 5 

Children 8 to 13 years (inclusive) old 6 

Children 14 to 17 years (inclusive) old 7 

Thus the average child of 6, 7, 8, and 9 years (chronological age) 
exceeded the memory span as given by Strong, and the average child 
of 12 and 13 years did not attain the memory span as given by 
Strong. Whether this indicates that Strong's conclusion as to the 
memory span at different ages should be revised or whether it 
indicates a precocity of the younger children and a retardation of 
the older children studied, or a difference of results due to different 
"stage settings" may be left suh judice. 

Comjmrison of sanitary groups. — In a former article^ it was shown 
that children from sewered homes advance, on an average, more 
rapidly in school grades than do the children from homes provided 
with privies. 

1 Public Health Reports, v. 30 (28), July 9. 1915, pp. 2060-2067. 



MEMORY TESTS OF SCHOOL CHILDREN. 9 

If the sanitary groups in the memory-span tabulations are com- 
pared for the total years (in order to obtain larger groups than are 
furnished by the quarter-year divisions), it is seen that there are 48 
sanitary groups (24 ''S" groups, 24 ''P" groups) that can be com- 
pared. In these 24 comparisons (12 of boys, 12 of girls), 14 S groups 
(7 of boys, 7 of girls) excel as compared with 10 P groups (5 of boys, 
5 of girls) that excel; but the S groups are larger than the P groups. 

So far as it is possible to judge, on basis of the 1,585 white children 
(751 boys, 834 girls) studied, the children from sewered homes aver- 
age a higher memory span than do the corresponding children from 
privy homes. It is further worthy of notice that in at least 5 of the 
P groups that stand higher than the correspondmg S groups the num- 
ber of children in the P groups is so small (one-ninth or less) as com- 
pared with the corresponding S groups that the value of the com- 
parison in these 5 groups is materially reduced." For instance — 

Boys 14 P contains only 3 pupils as compared with 14 S (38 pupils). 
Boys 15 P contains only 4 pupils as compared with 15 S (41 pupils). 
Boys 16 P contains only 3 pupils as compared with 16 S (31 pupils). 
Girls 6 P contains only 3 pupils as compared with 6 S (27 pupils). 
Girls 17 P contains only 1 pupil as compared with 17 S (29 pupils). 

The same statements made in a former article, in connection Vvdth 
the grade advancements, hold in connection with the memory spans, 
namely, that numerous sociological factors come into consideration 
in this connection and that the sanitation, with its attendant results, 
is only one of these factors. It is, however, clear that the children 
from the homes with b tter sanitation actually averaged a higher 
memory span than did the hildren from homes with poorer sanitation. 

Cases of Intestinal Infections. 

Hookworms. — Of the 83 white p j^jiIs (55 boys, 28 girls) who showed 
hookworm infection, memory-span results are available for 52 
(36 boys, 16 girls). Computing these results on basis of the average 
for the separate sex, total-year, and saiiitary groups, these 52 children 
were entitled to a total memory span of 343.24 (boys 237.20, girls 
106.4); they actually made a total of 339 (boys 232, girls 107); thus 
they showed an average loss of 0.08 (boys 0.14 loss, girls 0.06 gain). 

Ascaris. — Of the 58 pupils (46 boys, 12 girls) who showed Ascans 
infection, memory-span results are available for 38 (29 boys, 9 girls). 
Comjjuting these results on basis of the average for the separate sex, 
total-year, and sanitary groups, these 38 pupils were entitled to a 
total memory span of 245.23 (boys 187.60, girls 57.63); they actually 
made a total of 250 (boys 197, girls 53) ; thus they showed an average 
of 0.13 gain (boys 0.32 gain, ghls 0.51 loss). 

Lamllia. — Of the 99 pupils (71 boys, 28 girls) who showed Lamblia 
infection, memory-span results are available for 67 (50 boys, 17 girls). 



10 MEMORY TESTS OF SCHOOL CHILDEEN. 

Computing these results on basis of the average for the separate sex, 
total-year, and sanitary groups, these 67 pupils were entitled to a 
total memory span of 441.36 (boys 325.93, girls 115.43) ; they actually 
made a total of 444 (boys 331, girls 113) ; thus they showed an average 
of 0.04 gain (boys 0.10 gain, girls 0.14 loss). 

Endamceha coli. — Of the 68 pupils (46 boys, 22 girls) who showed 
infection with Endamaha coli, memory-span results are available for 
55 (39 boys, 16 girls). Computing these results on basis of the 
average for the separate sex, total-year, and sanitary groups, these 
55 pupils were entitled to a total memory span of 367.29 (boys 259.31, 
ghls 107.98); they actually made a total of 376 (boys 266, gnls 110); 
thus they showed an average gain of 0.15 (boys 0.17, girls 0.13). 

Other 'parasites. — The infections with Trichuris, Trichomonas, and 
Hymenolepis are too small in number to justify conclusions. 

Conclusions. — The results obtained in pupils with parasitic infec- 
tions (in general, hght cases) do not show that the known infections 
with hookworms, eelworms, Lamblia, or Endamoeha coli had any mate- 
rial influence in inhibiting the average memory span of their respec- 
tive groups. It should, however, be recalled that only 31.7 per cent of 
the white pupils submitted specimens for microscopic examination, 
and we have no way of knowing whether or not intestinal infections 
were present in the two- thirds who were not examined for intestinal 

parasites. 

Summary. 

White urban school children in the sand district of the South may 
be reasonably expected to average the following memory spans: 
6 and 7 years, chronological age, 5 numbers; 8 to 13 years, inclusive, 
6 numbers; 14 to 17 years, inclusive, 7 numbers. 

The children from homes with better sanitation can reasonably be 
expected to excel in memory span those from homes with poorer 
sanitation approximately in the ratio of 14 to 10, calculated on basis 
of total year periods. 

The evidence at hand does not show that hght infections with 
hookworms (Necator), eelworms (Ascaris), Lamhlia, or Endamoeha 
coli had any material effect in inhibiting the memory span of the 
children who were found to harbor these parasites, when their memory 
.span was compared with the average of the children of their respec- 
tive groups. This conclusion can not be extended at present to cases 
of severer infection with these parasites. 

o 



-XDKHKT ui- CONGRESS 



019 820 175 3 



L 



31 



LIBRARY OF CONGRESS 



019 820 175 3 



HoUinger Corp. 
pH8.5 



